A PostCSS plugin to use rgb and rgba with hex values Installation npm install postcss-rgb Example div { background: rgba(black, 0.4)} will produce div { background: rgba(0, 0, 0, 0.4);} Usage Using Gulp. var gulp = require('gulp'), postcss = require('gulp-postcss'), rgb = require('postcss-rgb'); gulp.task('css', function() { gulp.src('path/to/dev/css'). .pipe(postcss({ rgb })) .pipe(gulp.dest('path/to/build/css'));}); // rest of the gulp file